Mega-spined trilobite: Acidaspis

219Kb
download
[click and drag the image to rotate the exhibit]

A fossil 'odontopleurid' trilobite, named Acidaspis, from Devonian rocks
in Morocco. The spines are almost as long as the body.

These
spines may well have been used in defence, to discourage
predators from attacking the trilobite. Trilobites from
the Cambrian Period are apparently much less specialised.
Perhaps the development of early jawed fish created
the need for defensive parts.